Biochar reduces the efficiency of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) mitigating N2O emissions

Abstract

Among strategies suggested to decrease agricultural soil N2O losses, the use of nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) has been proposed. However, the efficiency of DMPP might be affected by soil amendments, such as biochar, which has been shown to reduce N2O emissions. This study evaluated the synergic effect of a woody biochar applied with DMPP on soil N2O emissions. A incubation study was conducted with a silt loam soil and a biochar obtained from Pinus taeda at 500 °C. Two biochar rates (0 and 2% (w/w)) and three different nitrogen treatments (unfertilized, fertilized and fertilized + DMPP) were assayed under two contrasting soil water content levels (40% and 80% of water filled pore space (WFPS)) over a 163 day incubation period. Results showed that DMPP reduced N2O emissions by reducing ammonia-oxidizing bacteria (AOB) populations and promoting the last step of denitrification (measured by the ratio nosZI + nosZII/nirS + nirK genes). Biochar mitigated N2O emissions only at 40% WFPS due to a reduction in AOB population. However, when DMPP was applied to the biochar amended soil, a counteracting effect was observed, since the N2O mitigation induced by DMPP was lower than in control soil, demonstrating that this biochar diminishes the efficiency of the DMPP both at low and high soil water contents.

Co-application of high temperature biochar with 3,4-dimethylpyrazole-phosphate treated ammonium sulphate improves nitrogen use efficiency in maize

“…Therefore, biochar could further extend, or delay the nitrification inhibition induced by DMPP and slows the release of nitrate for the later stage of maize growth 37 . This output is in complete disagreement with the findings of Sheikhi et al 38 , Fuertes-Mendizábal et al 39 , and Keiblinger et al 40 , where authors presented the negative interaction of DMPP with biochar.…”

“…Some previously published works of other studies seem quite opposing to our finding in some ways, which is attributed only to the higher production temperature of biochar (700 °C) used in this study. For example, the adsorption of DMPP by lower temperature produced biochar was reported for the biochars pyrolyzed at 450 °C 38 , 500 °C 39 , 400 °C and 525 °C 40 . In those studies, the presence of low NH 4 + concentration in the treatments containing DMPP with biochar seems holding back the intended use of DMPP to limit the process of nitrification.…”

“…Further, the lower temperature produced biochar can adsorb DMPP. Fuertes-Mendizábal et al 39 reported the adsorption of DMPP driven by the oxygen containing functional groups, more specifically carboxyl groups, of the lower temperature produced biochar (500 °C) used in their study. This is in the agreement with the finding of Keiblinger et al 40 , reported a greater adsorption of DMPP by the biochar produced at 400 °C than the biochar produced from the same feedstock at the higher temperature (525 °C).…”

Feedstock choice, pyrolysis temperature and type influence biochar characteristics: a comprehensive meta-data analysis review

“…Over shorter time scales (e.g., one to several years), biochars have been proven to improve environmental quality by sorbing heavy metals and organic contaminants (e.g., Sigua et al 2019;Cui et al 2019;Novak et al 2019a), positively affect soil water relations (e.g., Lentz et al 2019;Kammann et al 2011), reduce greenhouse gas emissions (e.g., Fuertes-Mendizábal et al 2019;Borchard et al 2018;Jeffery et al 2016), and improve crop growth (e.g., Laird et al 2017;Novak et al 2016;Liu et al 2013). Although creation of biochars for the above purposes may seem simply based on feedstock selection, biochar production for environmental improvements is complex.…”

Climate-Smart Agriculture Practices for Mitigating Greenhouse Gas Emissions

“…Management practices can also affect the efficiency of nitrification inhibitors. For example, biochar application to the soil has been shown to decrease the efficiency of DMPP both at 40 and 80% of water-filled pore space (WFPS) in a laboratory incubation study (Fuertes-Mendizábal et al 2019). The use of nitrification inhibitors increases crop yield and NUE, but the effectiveness was greatest when they are used in coarse-textured soils, irrigated systems and/or crops receiving high rates of N fertiliser input (Abalos et al 2014).…”